linux-kernel - [PATCH 2/9] x86/uaccess: Enable hardened usercopy

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Message-Id: <1467843928-29351-3-git-send-email-keescook@chromium.org>
Date:	Wed,  6 Jul 2016 15:25:21 -0700
From:	Kees Cook <keescook@...omium.org>
To:	linux-kernel@...r.kernel.org
Cc:	Kees Cook <keescook@...omium.org>, Rik van Riel <riel@...hat.com>,
	Casey Schaufler <casey@...aufler-ca.com>,
	PaX Team <pageexec@...email.hu>,
	Brad Spengler <spender@...ecurity.net>,
	Russell King <linux@...linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	"David S. Miller" <davem@...emloft.net>, x86@...nel.org,
	Christoph Lameter <cl@...ux.com>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...e.de>,
	Mathias Krause <minipli@...glemail.com>,
	Jan Kara <jack@...e.cz>, Vitaly Wool <vitalywool@...il.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Laura Abbott <labbott@...oraproject.org>,
	linux-arm-kernel@...ts.infradead.org, linux-ia64@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, sparclinux@...r.kernel.org,
	linux-arch@...r.kernel.org, linux-mm@...ck.org,
	kernel-hardening@...ts.openwall.com
Subject: [PATCH 2/9] x86/uaccess: Enable hardened usercopy

Enables CONFIG_HARDENED_USERCOPY checks on x86. This is done both in
copy_*_user() and __copy_*_user() because copy_*_user() actually calls
down to _copy_*_user() and not __copy_*_user().

Based on code from PaX and grsecurity.

Signed-off-by: Kees Cook <keescook@...omium.org>
---
 arch/x86/Kconfig                  |  2 ++
 arch/x86/include/asm/uaccess.h    | 10 ++++++----
 arch/x86/include/asm/uaccess_32.h |  2 ++
 arch/x86/include/asm/uaccess_64.h |  2 ++
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 0a7b885964ba..2a66b73a996d 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -80,11 +80,13 @@ config X86
 	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
 	select HAVE_AOUT			if X86_32
 	select HAVE_ARCH_AUDITSYSCALL
+	select HAVE_ARCH_HARDENED_USERCOPY
 	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_KASAN			if X86_64 && SPARSEMEM_VMEMMAP
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_KMEMCHECK
+	select HAVE_ARCH_LINEAR_KERNEL_MAPPING	if X86_64
 	select HAVE_ARCH_MMAP_RND_BITS		if MMU
 	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if MMU && COMPAT
 	select HAVE_ARCH_SECCOMP_FILTER
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 2982387ba817..aa9cc58409c6 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -742,9 +742,10 @@ copy_from_user(void *to, const void __user *from, unsigned long n)
 	 * case, and do only runtime checking for non-constant sizes.
 	 */
 
-	if (likely(sz < 0 || sz >= n))
+	if (likely(sz < 0 || sz >= n)) {
+		check_object_size(to, n, false);
 		n = _copy_from_user(to, from, n);
-	else if(__builtin_constant_p(n))
+	} else if(__builtin_constant_p(n))
 		copy_from_user_overflow();
 	else
 		__copy_from_user_overflow(sz, n);
@@ -762,9 +763,10 @@ copy_to_user(void __user *to, const void *from, unsigned long n)
 	might_fault();
 
 	/* See the comment in copy_from_user() above. */
-	if (likely(sz < 0 || sz >= n))
+	if (likely(sz < 0 || sz >= n)) {
+		check_object_size(from, n, true);
 		n = _copy_to_user(to, from, n);
-	else if(__builtin_constant_p(n))
+	} else if(__builtin_constant_p(n))
 		copy_to_user_overflow();
 	else
 		__copy_to_user_overflow(sz, n);
diff --git a/arch/x86/include/asm/uaccess_32.h b/arch/x86/include/asm/uaccess_32.h
index 4b32da24faaf..7d3bdd1ed697 100644
--- a/arch/x86/include/asm/uaccess_32.h
+++ b/arch/x86/include/asm/uaccess_32.h
@@ -37,6 +37,7 @@ unsigned long __must_check __copy_from_user_ll_nocache_nozero
 static __always_inline unsigned long __must_check
 __copy_to_user_inatomic(void __user *to, const void *from, unsigned long n)
 {
+	check_object_size(from, n, true);
 	return __copy_to_user_ll(to, from, n);
 }
 
@@ -95,6 +96,7 @@ static __always_inline unsigned long
 __copy_from_user(void *to, const void __user *from, unsigned long n)
 {
 	might_fault();
+	check_object_size(to, n, false);
 	if (__builtin_constant_p(n)) {
 		unsigned long ret;
 
diff --git a/arch/x86/include/asm/uaccess_64.h b/arch/x86/include/asm/uaccess_64.h
index 2eac2aa3e37f..673059a109fe 100644
--- a/arch/x86/include/asm/uaccess_64.h
+++ b/arch/x86/include/asm/uaccess_64.h
@@ -54,6 +54,7 @@ int __copy_from_user_nocheck(void *dst, const void __user *src, unsigned size)
 {
 	int ret = 0;
 
+	check_object_size(dst, size, false);
 	if (!__builtin_constant_p(size))
 		return copy_user_generic(dst, (__force void *)src, size);
 	switch (size) {
@@ -119,6 +120,7 @@ int __copy_to_user_nocheck(void __user *dst, const void *src, unsigned size)
 {
 	int ret = 0;
 
+	check_object_size(src, size, true);
 	if (!__builtin_constant_p(size))
 		return copy_user_generic((__force void *)dst, src, size);
 	switch (size) {
-- 
2.7.4